1. Field of the Invention
This invention relates to stable hydrosulfite-based compositions particularly useful for treating dyed or tinted textiles.
2. Description of the Prior Art
The use of hydrosulfites in dyeing processes and in treating both undyed and dyed textiles is known. Illustrative of these uses are the disclosures in the following known patents.
U.S. Pat. No. 1,181,906 discloses the use of alkali metal hydrosulfite in dyeing animal textile fibers with sulfur dyestuffs.
U.S. Pat. No. 1,847,698 discloses bleaching the non-immunized cotton component of a composite fabric with hydrosulfite after printing or dyeing.
U.S. Pat No. 1,959,406 discloses the use of sodium hydrosulfite for pre-shrinking textiles.
U.S. Pat. No. 3,127,231 discloses vat dyeing or dye stripping with a reducing composition including hydrosulfite, sodium borohydride, and alkali metal hydroxide.
U.S. Pat. No. 3,567,589 discloses the use of a caustic-hydrosulfite reducing bath in dyeing polyester/cotton fabrics with vat/disperse dye systems.
U.S. Pat. No. 3,607,373 discloses treating polyolefin fibers with aqueous metal hydrosulfite to improve thermal stability.
In treating dyed textiles, hydrosulfites have been employed for afterclearing and scouring dyed synthetic textiles, especially dyed polyesters. In particular, compositions have been used comprising solium hydrosulfite, sodium hydroxide or sodium carbonate, detergent, and sequestering agent (e.g., EDTA or sodium hexametaphosphate) added separately to and mixed in the final rinse after dyeing. While effective, this prior practice of separately adding each ingredient to and mixing in the rinse bath to form the clearing and scouring composition is undesirable because it is time consuming, inaccurate, and inefficient. For example, caking of the ingredients during mixing occurs if the water temperature is not exactly right; and the hydrosulfite is unstable and loses its strength in environments having any appreciable humidity. Further, it is hazardous due to the corrosive nature of the caustic and the inflammability of the hydrosulfite. Illustrative of known prior art employing such a procedure are French Pat. No. 1,202,744, U.S. Pat. No. 3,174,816, Canadian 888,605 (hydrosulfite and detergent used as a premixed material), and CHEMIFASERN (W. Kunz), Vol. 20, No. 5, 1970, pages 398-401.
In addition, aqueous hydrosulfite solutions, like those used for clearing and scouring, have been employed for decoloring or removing the tint from synthetic fibers tint dyed for textiletype and lot identification by the fiber manufacturer, and for stripping dyed synthetic textiles to lighten their hue. In so far as the applicant knows, these further applications of hydrosulfite have also employed separate additions and mixing of ingredients at the time of use, and hence have the same inherent disadvantages and problems.
The problem of hydrosulfite instability and/or inflammability has been addressed by the prior art and has been alleviated with varying degrees of success by admixing the hydrosulfite with:
a. Anhydrous sodium or potassium salts of a benzoic acid or an alkanoic acid containing 1 to 18 carbon atoms (U.S. Pat. No. 3,054,658); or PA1 b. Dry alkali-metal compound(s) (British Pat. No. 384,903); or PA1 c. Non-ionic, cationic or amphoteric surfactants (Canadian Pat. No. 888,605). PA1 a. 2% o.w.f. of Disperse Blue 56 (Resolin Blue FBLD), or PA1 b. 2% o.w.f. of Disperse Red 78 (Artisil Scarlet 2GFL) PA1 a. 4% o.w.f. of Disperse Blue 56(Resolin Blue FBLD), or PA1 b. 2.5% o.w.f. of Dispersed Red 78 (Artisil Scarlet 2GFL)
Other stabilizers are disclosed in U.S. Pat. No. 3,794,738; U.S. Pat. No. 3,669,895; U.S. Pat. No. 2,516,321; U.S. Pat. No. 3,819,807; and U.S. Pat. No. 3,474,037. Of these, only Canadian Pat. No. 888,605 appears to teach that the disclosed stablized hydrosulfite mixture can be used as a replacement for unstabilized hydrosulfite in aqueous baths used for cleaning and scouring or stripping dyed synthetic textiles. Such baths would be expected to still require the separate addition of at least caustic and, if necessary, sequestering agent.